Combination solenoid speaker



Nov. 20, 1945. sc w z 2,389,212

COMBINATION SOLENOID SPEAKER Filed Sept. 2, 1942 m w; I

Gttornegs 1 Patented Nov. 20, 1945 COMBINATION SOLENOID SPEAKER Bertram A. Schwarz, Kokomo, Ind.,- assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 2, 1942, Serial No. 457,003

9 Claims.

This invention relates to magnetic or solenoid means and more specifically to the use of the solenoid for the loud speaker in a radio receiver for a plurality of uses. There are of course in radio receiver construction a number of instances in which a-magnetic field may be used to accomplish useful results. In substantially all of the radio receivers which are now on the market there is provided a large solenoid coil which operates the speaker of the receiver. This coil is usually of sufiicient size and generates a sufficiently strong field to operate other mechanisms associated with the receiver when desired. There may be a large number of instances in which magnetically controlled means are desirable and as an example there may be mentioned the actuation of tuning mechanism and short circuit protection and of course there may be many others.

It is therefore an object of my invention to provide means for utilizing a magnetic field for a plurality of difierent purposes.

It is a further object of my invention to provide means for utilizing a magnetic field of a speaker unit in a radio receiver for controlling other portions of the system.

It is a still further object of my invention to provide means for utilizing the speaker field of a radio receiver to automatically tune thesame to different stations.

It is a still further object of my invention to provide means for utilizing the speaker field of a radio receiver as a protective device.

With these and other objects in view which will become apparent as the specification proceeds, my invention will be best understood by reference to the following specification and claims and the illustrations in the accompanying drawing, inwhich:

Figure 1 is a schematic view illustrating the actuation by the speaker coil of tuning means for a radio receiver;

Figure 2 is a schematic View illustrating the speaker coil actuation of a protective control system; and

Figure 3 is a schematic wiring diagram showing a modified form of circuit.

Referring now more specifically to Figure 1, there is therein illustrated a speaker housing 2 which encloses a loud speaker 4, the same having mounted at its base a cylindricalform 6 supporting a movable actuating coil which projects into a circular opening 8 in the solenoid case it]. Within the solenoid case I is mounted the main solenoid coil l2 which in this instance is shown in the form of a torus and has a central aperture therethrough. Mounted within this central aperture is a sleeve I4 which is formed of a non-magnetic material such as brass and which stationarily supports at one end a core it which is adapted to project up within the end of the cylindrical form 6 to concentrate the magnetic field suficiently about this actuating coil for the speaker cone.

As will be noticed from the drawing, this core it only extends axially one half way within the coil and has a center depression l8. Mounted within the other portion of the coil is a movable core member 20 having a projecting tip which is adapted to enter the conical depression l8 in the stationary core. The movable core 20 slides within the sleeve l4 and may move in or out, depending upon the strength of the ma netic field 12. This core member has a projecting portion 22 to which is secured one end of a tension spring 24 which is anchored to a frame support such as diagrammatically shown at 26. Thus with no field being generated by the coil, the spring will pull the core member 20 outwardly from its association with the coil and when voltage is applied to the coil l2 thev field will be sufficient to overcome the strength of the spring and Withdraw the movable core 20. to a position within the coil.

This action may be utilized to perform any desired operation of other portions of the associated apparatus, but it is shown as an illustration here that this action may operate a tuning mechanism. Pivotally secured to the movable core at 28 is one end of a lever .30 which is pivoted about a center fixed pivot 32 at some point of the frame and whose outer end is pivotally connected at 34 to a connecting lever 36 which is likewise pivotally connected at 38 to a third lever 40. This third lever is supported upon a stationaiy pivot-42 and its opposite end actuates the tuning means.

The tuning means here shown diagrammatically i mounted upon a frame 44 and consists of a plurality of parallel longitudinally movable rods 46 each having thereon a threaded portion -58 carrying an adjustable nut 50. These nuts tend to rotate a treadle system indicated at 52 and described in detail in a copending application Serial No. 319,044, filed February 15, 1940 in the names of Bertram A. Schwarz and Ludwig Fichter, and entitled Tuning mechanism, so that it is thought that no more detail need to be added at this point since the tuning mechanism per se forms no part of this invention. Upon the reciprocation of one of the rods 46, the nut 50 will force the treadle system 52 inwardly to a certain redetermined point and thus through the connections 54 will move tuning means 56 which are here shown as comminuted cores associated with tuning coil 58 to tune the receiver. The final point of index is determined by the locking button 60 which snaps over the end of a spring biased pivoted plate 62, and thus definitely determines the longitudinal position of the rod 46, the index position being determined by the position of the traveling nut 50 thereon.

On the outer end of the rod 46 there is a push button 64 which is grooved to cooperate with ribs 66 on the end of the shaft 46 so that the same may be rotated thereby, but there may be relative axial movement therebetween. A sprin 68 tends to maintain the button in its outer position, the frame shown in dotted lines preventing the same from being expelled from the end of the shaft. There are a plurality of these assemblies in alignment. The flange I on each of the buttons 64 operates a switch I2, which is in the voltage supply line 14-16, from the radio receiver. Line I6 is connected to one side of the solenoid coil I2, the other side being connected by line I6 back to the radio receiver.

The operation of the device is as follows:

Let us suppose that the set is operating and that signals are being reproduced by the speaker 4. The operator then desires to tune the receiver to a different station and therefore presses against a selected one of the plurality of push buttons 64. This first pushes its rod 46 slightly inward and next opens switch I2 which deenergizes the solenoid coil I2. This causes the spring 24 to pull the movable core 20 from the coil I2 and at the same time operate the lever system 303640. This causes the end of the lever 40 to swing downwardly to the full line position, by which action it engages the rear face of the tip 60 of the longitudinally movable assembly and pulls it over the end of the lockin plate 62 into the new indexed tunin position. Thus it is only necessary to depress the push button 64 slightly to give the longitudinal rod a slight movement inwardly and open the switch I2 and the complete tuning action will be obtained through movement of the core 20 by the spring 24. It should be mentioned at this point that the end of the lever 40 extends horizontally across the tops of the plurality of tuning rod at right angles to the plane of the drawing, and of course engages only the one which is initially depressed a slight amount to throw it out of line as the lever turns. In this manner the magnetic field of the coil I2 of the speaker is utilized to automatically tune the radio receiver by only a slight inward push on any one of the push buttons.

A second use to which the magnetic field of the speaker may be put is shown in Figure 2. In this instance here again is shown a loud speaker having an operating magnetic coil I 2, a stationary or rigid core member I6, and a movable reciprocating core 20. There is secured to the movable core a switch arm 80 carrying a movable contact 82 which is adapted to cooperate with a contact 84 connected to a line 86 from the radio receiver. A source of power 88 is shown connected by line 90 to the movable arm 80, but it is obvious that the source of power may be in the radio receiver and that this portion of the circuit may merely go to ground. Here again the movable core is sprin biased by a tension spring 24 which is anchored as at 26 to the frame of the receiver. There is also mounted in the frame a reciprocating push button 92 whose inner end lies adjacent the movable switch arm and upon depression of the same will reset the two switch contacts in closed position.

The operation of this system is as follows:

Assuming that the set is in operation and that a short circuit develops, the current normally applied to the speaker coil I2 will be decreased and the field will be so weakened that the coil spring 24 will overcome the retentive action of the field and the core 20 will move to the left as shown in Figure 2. This action will cause a break in a main power line of the radio receiver, causing the same to be put out of service, or completely deenergized. This will prevent any damage to the set if a short appears at any particular point and when the set has been investigated and the trouble removed, pressure upon the manual reset 92 will force the core 20 again within its coil I2 and close the switch 82-84. Ln this manner the use of the magnetic field of the speaker coil is used for protective purposes.

Figure 3 discloses a system whereby a stronger spring 24 may be used than in the former disclosure where it is desired to have a very strong force applied to the movable core to withdraw it from its associated coil. In that instance the speaker coil is tapped to form two portions 94 and 96, the tap being connected by line 98 to contact I00. The upper end of the speaker coil is connected by line I02 to contact I04 and oscillated between the two contacts I00 and I04 is a movable contact I06 mounted upon a movable arm I08 which is connected by line H0 to one switch contact II2, the cooperating switch contact II4 of which is movable and operated by a push button I I6 and also connected by line I I8 to one side of a voltage source. The opposite side of the voltage source is connected by line I20 to the opposite end of the speaker coil. The movable switch arm I08 in this instance is carried by the movable core 20 of the speaker coil.

With the use of this circuit a heavier spring may be used and more power for returning the core to its inward position is obtained in the following manner: I

With the core in its inner position and the system in the condition shown in Figure 3, that is, with switches II2-I I4 closed and switches IDS-I04 closed, the core 20 would be maintained within the housing by the normal strength of the speaker coil. If now, either for resetting tuning purposes or for protective purposes, the core 20 is withdrawn by the spring 24, which may be accomplished as diagrammatically shown in this instance by the means II6 opening switch II2I I4, the switch I04I06 will be broken but a contact will be made between switch I00 and contact I06 so that when the switch II2-I I4 is again closed to enable the coil I2 to pull the core 20 back within the central housing, only section 94 of the speaker coil will be energized for this purpose and thus a larger current will pass through these turns and a larger magnetic force will be applied to pull the core back in. Since a larger force is thus provided, a heavier spring 24 may be used, and therefore a quicker action may be obtained in either direction. The reason for the higher magnetic field being set up by a smaller number of turns is that since the coil is a multilayer one, in tapping down radially into the same the resistance decreases faster than the number of turns and therefore actually a larger number of ampere turns is obtained. With this meansv I have provided faster action of this member.

It will thus be evident from the above that there has been illustrated herein several means in which the magnetic field set up by the speaker coil can be used to carry out certain additional desired functions without the necessity of providing any additional coil means for such uses and therefore with no additional equipment a plurality of functions are served by an existing portion of the apparatus.

I claim:

1. In a control system for a radio receiver having a speaker and tuning means, a solenoid coil for the speaker, a stationary core mounted within the coil, a speaker coil mounted adjacent the solenoid and core to actuate the speaker to produce audible waves, a relatively movable core mounted within the solenoid and affected by the magnetic field thereof to move the same in one direction, biasing means urging the core in the opposite direction, and means actuated by movement of the movable core to operate the tuning means.

2. In a control system for a radio receiver having a speaker and tuning means, a solenoid coil for the speaker, a stationary core mounted within the coil, a speaker coil mounted adjacent the solenoid and core to actuate the speaker to produce audible waves, a relatively movable core mounted within the solenoid and affected by the magnetic field thereof to move the same in one direction, biasing means urging the core in the opposite direction, and control means for the radio receiver operated by the movement of the movable core.

3. In a control system for a radio receiver having a speaker, ,an electromagnetic operating coil providing a field for the speaker, auxiliary core means actuated by said coil and means for controlling desired portions of the receiver actuated by the auxiliary core.

4. In a control system for a radio receiver having a speaker, an electromagnetic coil to provide a magnetic field for said speaker, an auxiliary movable core adapted to be attracted by the field of said coil, means for biasing said cor away from said coil whereby when current is applied to the coil the core will be attracted toward the same, but when no current passes, the biasing means will move the core away from the coil, and control means for said receiver actuated by said core movement.

5. In a control system for radio receiver having a speaker, an electromagnetic coil providing a magnetic field for said speaker, automatic tuning means for said receiver and means actuated by said field to operate said tuning means.

6. In a radio receiver, a speaker, means for tuning said radio receiver to a plurality of predetermined wave lengths and a single electromagnetic means creating a magnetic field for the speaker and operating the tuning means.

7. In a control system for a radio receiver having a speaker, an electromagnetic field coil for said speaker, a biased auxiliary movable core attracted by the field of said coil and a safety switch for said receiver operated by said auxiliary core movement.

8. In a control system for a radio receiver having a speaker, an operating field coil for said speaker, an auxiliary movable core attracted by the field of said coil, spring biasing means for said core .to bias the same away from the coil field and a safety switch actuated by the movement of the auxiliary core.

9. In a control system for a radio receiver having a speaker, an operating field coil for said speaker, an auxiliary movable core attracted by the field of said coil, spring biasing means for said core to bias the same away from the coil field, a safety switch actuated by the movement of the auxiliary core, and resetting means for the safety switch.

BERTRAM A. SCHWARZ. 

